Recently due to development of broadband internet, image processing and display technologies, watching broadcast programs or movies conveniently at home is a popular scene of ordinary households. As the dissemination of digital TV is prevalent, large-screen TVs are generally preferred in the market. But in case displaying a specific part of a scene like human face having HD (High Definition) resolution in large-screen displays, squared pixels are revealed so that image quality is degraded. Therefore, UHD (Ultra High Definition) video service having 4 times to 16 times resolution compared with the conventional HD video attracts public attention as a next generation broadcasting technology. The UHD video can provide audience with sense of reality so that it is expected to use in various areas including broadcasting, teleconference, education, medicine, and game. But one of the problems in providing UHD video service is the increase of data volume. Table 1 shows SMPTE standard regarding the transmission of SD-SDI, HD-SDI, and UHD-SDI video formats. For example, 4K UHD video (3840*2160, 60 frames), defined as SMPTE ST-2082, requires bandwidth of 12 Gbits/s.
TABLE 1StandardNameBitratesVideo formatsSMPTE 259MSD-SDI270 Mbit/s,480i, 576i360 Mbit/s,143 Mbit/sand 177 Mbit/sSMPTE 344MED-SDI540 Mbit/s480p, 576pSMPTE 292MHD-SDI1.485 Gbit/s, and720p, 1080i1.485/1.001 Gbit/sSMPTE 372MDual Link2.970 Gbit/s, and1080pHD-SDI2.970/1.001 Gbit/sSMPTE 424M3G-SDI2.970 Gbit/s, and1080p2.970/1.001 Gbit/sSMPTE ST-20816G UHD-SDI6 Gbit/s4Kp30SMPTE ST-208212G UHD-SDI12 Gbit/s4Kp60
Hence, to perform switching or routing the videos having 12 G UHD-SDI format, it is required to use switches or routers more than 40 G bandwidth since switches or routers having 10 G bandwidth cannot process a single channel. In this case, it is difficult to provide video service since network infrastructure supporting 40 G bandwidth including switches and routers is not sufficient and service provision cost is increased because single wideband traffic is processed.
Although there is a bandwidth problem in handling 12 G UHD-SDI with 10 G routers because of the required bandwidth for 12 G UHD-SDI, any device or method does not exist to handle 12 G UHD-SDI signal with multiple switches or routers having low bandwidth like 1 G or 2.5 G. In other words, any switch or router is not yet developed in which a broadband SDI signal having 12 G is divided into multiple relatively low bandwidth signals such as 1 G or 2.5 G and processed.
In addition, in case that the videos having large data size are compressed, converted into IP packets and then switching and routing are performed, using JPEG2000 algorithm is previously proposed but it has processing speed and delay problems in real-time switching/routing because it requires large amount of computations so that the processing is delayed.
Considering the current situation, the present invention proposes an apparatus for efficiently switching or routing UHD videos having large bandwidths and the method thereof, which decomposes image signal consisting of YCbCr type (e.g. 4:2:2 type) color format entered with SDI into Y component and C component, compresses the decomposed video signal components with one-dimensional compression (discrete cosine transform (DCT), discrete wavelet transform (DWT), quantization, scan, run-length coding (RLC), variable length coding (VLC), etc.), conversion of color format, or bit slice truncation (for example, removing part of a bit slice in the least significant bits of C components) for reducing the bandwidth, converts the components into IP packets and performs switching or routing of packets; then extracts Y component and C component or multiple bit slice components from switched or routed IP packets and restores the compressed data components into Y component and C component (with the methods, 1-D IDCT, 1-D DWT, inverse quantization, inverse scan, run-length decoding (RLD), variable length decoding (VLD), etc.); and combines the components into SDI format image signal and outputs the combined image signal.
One of the previous documents related with the technological issues in the present invention is Korea patent registration No. 1415281 (2014 Jun. 27), which relates to a virtual dynamic dual streaming (VDDS) system for video transmission of a HD-CCTV camera; it stores full HD video signals recorded through multiple HD-CCTV cameras at the storage media such as local hard disks of DVR (stream1), or converts the components into a full HD video signal while passing through a multiplexer (MUX) and transmits as a network stream through a video transmission module (stream2); and features a server that receives a full HD video signals transferred with the network streams through switches and then displays a full HD video composed by multiple channels from 1 to 16 channels on a monitor.
Another example of the previous documents related with the technological issues in the present invention is Korea patent publication No. 2011-0133854 (2011 Dec. 14) which relates to an apparatus transferring compressed videos using SDI and the method thereof; it features creating a separate compressed video data from a recorded video data, displaying a real-time video based on at least one camera and the video data received from the camera by sending the compressed video data inserted into auxiliary data packets of the video data, and extracting the compressed video data from the video data, and has the effect on lowering the system complexity of a digital video equipment by dividing the video compressing load to at least one of cameras.
In addition, Korea patent registration No. 1357182 (2014 Jan. 23) relates to a high-speed signal processing HD SDI video transmission apparatus, more specifically, which processes separately video, audio, data and Ethernet signals, controls transmission of each separated signal to the equipment or a device capable of the corresponding signal, and is adequate to preventing optical loss.
In addition, U.S. Pat. No. 7,756,118 (2010 Jul. 13) relates to a video switching system utilizing preferentially shared networks, which eventually controls multiple video/audio routing switches and IP routers connected to a router control system by remotely controlling the router control system through multiple user control panels, and is configured to modify priorities in processing network traffic in such a way that it assigns high priorities to important digital video data streams so as to transmit high priority video data streams first on backbone networks compared with other low priority data.
Though the above technical documentations deal with video transmission, switching, or routing method or equipment of SDI video format, they are limited to the videos having resolutions less than HD; and do not resolve the aforementioned problems or suggest a clue for solving the problems since they do not propose any method or equipment for switching or routing 12 G UHD-SDI videos requiring more bandwidths.
As described above, the present invention, therefore, proposes to an apparatus IP switching/routing image signals through bandwidth splitting and reduction and the method thereof, more specifically, which decomposes image signal consisting of YCbCr type color format entered with SDI into Y component and C component, or multiple bit slice components; converts the components into IP packets and performs switching or routing of packets; extracts Y component and C component from the switched or routed IP packets and combines the components into SDI format video signal and outputs the combined video signal.